Accessory for underfloor duct systems



June 9, 1931. H. s. WALKER 1,809,613

ACCESSORY FOR UNDERFLOOR DUCT SYSTEMS Filed March 15.1929

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mm if; 1 gygy f ATTORNEYS' Patented June 9, 1931 `UNITED STATES PATENT OFFICE Application led March 15, 1.929. Serial No. 347,199.

This invention relates to underiioor duct systems of the same general type as that de- Y scribed and claimed in my prior Patent N o.

1,592,548 issued July 13, 1926, and is concerned more particularly with an accessory to be used in such systems to close outlets, the use of which has been discontinued for any reason after the installation is completed. While the utility of the new accessory is not 10 limited to any particular system, the accessory will be described in a form especially for use in conjunction with the system of the patent, with the understanding that this is done merely for purposes of illustration. The system of ducts described in the patent includes a network of main and branch circuit ducts installed in the floor during construction, each duct being provided with a plurality of outlets spaced at predetermined uniform intervals. These outlets preferably take the'form of tubular inserts mounted in the top wall` of the duct and they are spaced at different distances in diiferent systems, depending on the character of the service which the system is to supply. For example, the space between adjacent inserts may be24 or 30 for ordinary purposes.

In the installation of the duct in a concrete ioor structure, it is the common practice to lay the ducts on the top of the rough floor slabv so that the ducts are embedded in the usual cinder fill and lie a substantial distance between the iinished ioor surface. The inserts project upwardly toward the Hoor surface and preferably terminate even with that surface, although they may terminate a short distance beneathit. The ends of the inserts at the timeof installation are closed by small caps which are slipped in the ends of the inserts and are readily removable therefrom.

After the finished floor surface is completed, it is customary to cover it with linoleum, although in some cases wood flooring is similarly employed. The main and branch circuit ducts lead to floor boxes, the tops of which are iush with the finished surface of the floor and the Wiring is drawn through the ducts in the ordinary way and connections made at the boxes. Whenever service isdesired at a point along a duct, an opening is made in the linoleum over one of the inserts, the cap. removed, the wires drawn through the opening and duct to the nearest box, Where. the connection is made. The connection is then completed by the use of a stand 6B pipe litting supported in the end of the insert, so as to lead the Wires out of the system to a point a few inches above the floor surface. This fitting is provided with a flange which overlies the linoleum and provides a substantially water-tight closure for the insert.. Y

In some instances, after such a connection has been made, it may be desirable to discontinue it, and whenever this is done, the stand pipe and the wires are removed. While the end of the insert may be closed by means of the original cap, there is still an opening in the floor covering which is undesirable.

The present invention is, therefore, directed to the provision of an accessory for use in a system of this sort which is to be used to provide a neat water-tight closure for the outlets, the use of which is discontinued, this `accessory not only serving to close the end of the insert but also closing and concealing the hole in the floor covering. This accessory may be readily introduced into the end of the insert and may then be secured firmly in positlon therein, sov that it will not become dislodged accidentally, The accessory may be ma e in different sizes for use with inserts of different diameters and it may be used in the insert alone or in conjunction withy -a bushing employed in certain large inserts l to reduce the internal diameter thereof.

For a better understanding of the inven tion, reference may be had to the accompanying drawings, in which ig. 1 is a sectional viewl throu h a duct 99 and insert with the accessory in pnce taken on the line 1 1 of Fig. 2;

Fig. 2 is a sectional view on the line 2 2 of Flg. l; andt Figs. 3 and tare longitudinal sectional(mi views through anjdut insert,

uses ofthe accessory; y

Referring now-to the drawings, the duct 10 is illustrated as being of rectangular cross-section of suitable dimensions. This'Y 10 showing other duct is provided with a plurality of inserts 11, one of which is shown. The insert is preferably a metal tube inserted into an opening in the top wall of the duct and having its lower end flanged over, as indicated at 12. In order to hold the insert in position in the duct Wall, it is provided with a circumferential rib 13, which engages the top Wall of the insert. The duct with its inserts is mounted in the floor structure 14 and the insert extends upwardly from the duct substantially to the surface of the floor. This insert is closed by a small removable cap during installation and prior to use.

When an outlet connection is to be made, the door covering 14', which is here illustrated as linoleum, is cut to provide an opening directly above the top of the insert, the location of the insert being determined by measuring along the duct from the adjacent box. The cap is then removed through the opening, the wiring fished through the insert and duct to the box where the connection is made, and the installation completed by a stand-pipe which is introduced into the end of the insert and has a flange which overlies the linoleum near the hole cut therethrough. When service is discontinued, the removal of the stand-pipe leaves the insert open. This open insert could be closed by means of the original cap, but if this were done a hole in the linoleum would be visible. In order to take care of this situation, the present accessory has been devised. This accessory consists of a tubular stem 15, the lower end of which is slotted, as indicated at 16. This stem has a diameter such that it may be readily received in the insert and the upper end of the stem is closed by a cap 17, which has a flange 18 which prollects beyond the wall 'of the stem. The cap is relatively thin and its thickness decreases from its center toward its periphery, so that at its outer edge its thickness is relatively small. Through an opening in the top of the cap extends a screw 19 which is threaded at its lower end into a 4 Wedge nut 20. This wedge nut has the shape of a truncated cone and its outer tapering wall 20 has an average diameter 'substantially that of the inner diameter of the stem 15.

When service is discontinued at any outlet and the Wiring and stand pipe removed, the stem of the accessory is inserted into the tubular insert, the nut at this time being free of the slotted end of the stem. When the accessory has been placed in position with the iiange 18 resting tightly against the floor covering, the screw is turned and the nut 20 is drawn up against the slotted end'of the stem engaging the inner edge thereof. By reason of the shape of the nut, the slotted portions ofthe stem are expanded by it so as to grip the inner Wall of the insert tightly.

Only a few turns of the screw is necessary for this purpose and the accessory is then locked rigidly in position and cannot be accidentally dislodged, By reason of the relative thickness of the cap 17 closing the upper end of the stem audits decreasing thickness toward the periphery, the presence of this cap above the floor covering is not at all objectionable and the flange protects the covering around the opening and at the same time provides a neat finish.

Should service be required at the outlet thus closed by the accessory, the accessory may be readily removed b-y turning the screw so as to release the nut from the edge of the stem. The accessory may then be readily removed by a suitable tool inserted beneath the edge of the flange.

As illustrated in Fig. 1, the accessory has a form suitable for use in an insert of ordinary size, the stem having an outer diameter substantially the same as the inner diameter of the insert. In some instances, duct systems are provided with large inserts, such as that shown at 21 (Fig. The insert here shownv is mounted in the Wall of the duct in the same manner as illustrated in Fig. 1 and the insert has a diameter at its top less than the diameter of the opening in the duct wall. This type of insert is frequently made with a thread 22 rolled in its wall near the top. In an insert of this type, it is customary to employ al bushing 23, the outer Wall of which is threaded to engage in the threads. of the insert. The bushing has an interior diameter substantially the same as the plain insert 11. Vith this bushing, t-he accessory may be used in the manner previously described, the expansion of the stem of the accemory causing it to grip the bushing rather than the inner Wall of theinsert. The accessory is used `in the same manner previously described.

In Fig. 4 there is shown a construction involving the use of an insert 24 of large diameter, the insert being of the same diameter from one end to the other and without the threads 22. In this case, the bushing 25 is a cylindrical form and held in place by friction. The accessory is used with this bushing in the manner above-described.

What I cla-im:

1. In an underfloor Wiring system, a duct in the floor structure, an open outlet 'element constituting a rigid extension from the duct toward the floor surface, and a closure for the end of the element comprising a part receivable intothe element, an end plate connected to said part and lying in contact with the door surface, said pla-te having a smooth substantially flat top of greater diameter than said part, and means for securing the closure firmly in position in the element.

2. In an underfloor wiring system, a duct y in the floor structure, an open outlet element extending from the duct toward the floor surface, and a closure for the end of the elel tially flat top of greater diameter than said part, and means carried by said closurefor expanding said part to cause it to grip said element whereby said closure is held firmly in position.

3. In an underfioor wiring system, a duct in the floor structure, an outlet element extending from the duct toward the floor surface, and a closure for the end of the element comprising a slotted hollow part receivable into the element, an end plate connected to said part and overlying the floor surface adjacent said element, said plate having a substantially flat smooth top and being of great-l er diameter than said part, and means engaging said ypart from within and operable to expand it to hold it in firm engagement with that part of the element in which it is received.

4. In an underfloor wiring system, a duct in the' floor structure, an outlet element extending from the duct toward the Hoor surface, and a closure for the end of the element comprising a tube receivable into the element an end plate closing one end of the tube and lying in contact with the Hoor surface, the open end of the tube being expansible and said plate havin a smooth substantially fiat top and being o? greater diameter than said tube, an expanding member carried by the closure and engaging the open end of the tube, and means carried by said closure operable from the ioor surface for actuating the said member.

5. In an underioor wiring system, a duct in the Hoor structure, an outlet fitting leading from the duct toward the floor surface, a bushing mounted in the tting, and a closure for the end of the bushing comprising a part receivable therein, a plate connected to said part and lying in contact with the floor surface around the bushing, and means for forcing said part into tight engagement with said bushing.

6. An accessory for closing anoutlet opening in an' underfloor wiring system which comprises a thinvplate of greater diameter than the opening, an extension from the plate adapted to enter the opening, and means carried by said plate for distorting the extension in tight engagement with the inner wall of the opening. v

v7. An accessory for closing an outlet opening in an .underiioor wiring system which comprises a plate of greater diameter than the opening having a smooth top and of tapering thickness from its center toward its periphery, an expansible extension from the plate adapted to enter the opening, and means carried by said plate for expanding the extension to cause it to engage the inner wall of the opening.

8. An accessory for closing an outlet open- I ing in an underfloor wiring system which comprises a plate of greater diameter than the opening, a tubular extension fromA the plate adapted to enter the opening and having a slotted end, a wedge member engageable with said slotted end to expand it into firm contact with the inner wall of. the opening and means carried by the plate for actuating the wedge member.

9- An accessory for closing an outlet opening in an underloor wiring system which comprises a plate of greater diameter than the opening, a tubular extension from the plate adapted to enter the opening and havlng a slotted end, a wedge nut engageable with said slotted end to expand it into firm contact with the inner wall of the opening, and a bolt carried by the plate and passing through the extension into the nut, the head of the bolt being received into an opening in the plate whereby the top of the bolt head is substantially flush with the plate.

10. In an underoor duct system, a duct in the floor structure below the surface thereof and having a outlet element constituting a rigid part of the duet and extending upwardly toward the floor surface, and a closure Afor the upper end of the element comprising a substantially Hat plate having a smooth top of greater diameter than the element, said top overlying the ioor surface adjacent said element and an extension from the under surface of the plate received in the end of the element and frictionally engaged therewith to hold the closure in position.

In testimony whereof I affix my signature.

' HERVEY S. WALKER.

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